Frederick County uses a 1,000-sq-ft threshold: smaller ADUs follow the permitted pathway and larger units require a special exception. See owner occupancy, parking, septic, impact fees and pending Bill 26-15.
Maryland ADU parking rules changed under HB 1466. See which counties require extra parking, where a parking study has been located, whether a waiver exists, and which jurisdictions are still in transition.
Yes, a Maryland garage can potentially become an ADU—but attached and detached garages follow different zoning paths. Check permits, setbacks, size, fire separation, utilities and county rules before converting.
Maryland jurisdictions must adopt local ADU laws by October 1, 2026 under HB 1466. Here is what the deadline actually requires, what the statute does not say happens on October 2, and how homeowners can navigate a county still in transition.
Anne Arundel currently allows interior, attached and detached ADUs with no additional parking. See the 800-sq-ft/50% detached cap, setbacks, permits and pending Bill 61-26 before paying for plans.
Baltimore County still uses its legacy accessory-apartment framework: interior units use a Use Permit, detached units require a Special Hearing plus Use Permit, and BCZR 400.4 sets current size and family-occupancy rules while the 2026 HB 1466 transition remains unresolved.
Compare Maryland ADU builders, modular providers and prefab kit options. See service scope, company-published pricing, Maryland licensing details and the questions to ask before signing a contract.
An ADU may be possible on private septic and well in Maryland, but capacity is not automatic. Check bedroom load, reserve area, perc/water-table testing, well setbacks and Health Department review before paying for plans.
How big can an ADU be in Maryland? Learn the 75% state rule, why Howard County uses exterior footprint, how Montgomery and Anne Arundel differ, and how to use SDAT without mistaking assessment data for a zoning measurement.
Prince George’s enacted CB-074 on September 29, 2026. Check the Council-listed November 16 effective date, commencement discrepancy, pending CB-092 provisions and permit steps.
